There are known in the prior art protective helmets which are provided with inner and outer visors, each of which is mounted on the helmet for movement between an inoperative or retracted position and an operative position at which it is disposed in front of the eyes of the person wearing the helmet. Customarily, one of the visors is tinted and the other visor is clear.
Various mechanisms are known in the prior art for selectively moving the inner and outer visors between the retracted position and the operative position. In one form of such a device, the helmet carries a housing which receives the visors in their inoperative position. The mechanism for moving the visors between the inner and outer positions incorporates an element which moves along a slot which extends in a fore and aft direction in the visor housing. An example of a mechanism of this sort is shown in Long et al U.S. Pat. No. 4,887,320. In some instances it may not be desirable to provide the helmet with a visor housing. Further, the particular operating mechanism including the member movable along the housing slot may be relatively inconvenient to use or too cumbersome.
Other forms of dual visor operating assemblies incorporate tracks extending in a fore and aft direction on the helmet shell and along which an operating member may slide in the course of moving a visor between its operative and inoperative positions. An example of such an arrangement is shown in Aileo U.S. Pat. No. 3,748,657. Again, for one reason or another, an operating mechanism of this type may not be desirable.
Still another mechanism for moving a visor between its operative and inoperative positions is shown in Luisada et al U.S. Pat. No. 3,636,565. That patent shows respective normally locked knobs on the sides of the helmet which can be released and individually rotated to move the respective inner and outer visors between their operative and inoperative positions. The mechanisms for achieving this result, however, are relatively complicated and expensive. In addition, they have a relatively high profile which in many instances is objectionable.
Still another form of dual visor operating mechanism is shown in our application Ser. No. 07/588,686, filed Sep. 26, 1990. In the arrangement shown therein, the respective inner and outer visors are pivotally supported for movement between their operative and inoperative positions by means of arbors located at the respective sides of the helmet shell. Releasable means is provided for frictionally clamping the visors to the arbors. This arrangement has the advantage of a low profile and infinite adjustment. A limitation, however, is the reliance on friction alone to hold the visor in its adjusted position. Stated otherwise, the arrangement does not provide a positive lock.
Still another form of dual visor operating mechanism is shown in Higgs U.S. Pat. No. 4,170,792. In the arrangement shown in the Higgs patent a clutch output member carried by the visor is rotatably supported on a cylindrical boss secured to the helmet shell. A cutout in the clutch output member receives a pair of balls which are urged by respective springs toward the central reduced diameter portion of the cutout to wedge the balls between the boss and the clutch output member. Any force exerted directly on the visor in an effort to move it up or down is resisted by the wedging action of the balls. A knob rotatably supported on the boss carries a clutch release element disposed between the balls and adapted to be moved into engagement with one or the other of the balls to move it against the action of its spring to a relatively larger diameter portion of the cutout to release the visor for movement with the knob to an adjusted position in which it is locked by the balls.
While the Higgs patent provides infinite adjustment of the position of the visor and a relatively positive locking action, it incorporates a number of defects. First, the operation of the device is not as smooth as is desired. More particularly, if the visor is in the up position and the person wearing the helmet actuates the knob to move the visor down, after the ball which had been holding the visor in the up position is moved to the release position, the weight of the visor itself causes it to get ahead of the wearer's movement of the knob so that the visor moves down in a number of steps. That is to say, in the course of the wearer's movement of the knob from the up position to the desired down position, the visor falls down a short distance, is locked again, is unlocked, and moves down another short distance through gravity until it is again stopped. This operation continues until the desired adjusted position is reached.